Research On Flight Characteristics,Guidance, And Control For A Dual-spin Projectile

In order to solve the problems about two-dimensional trajectory correction caused bythe high spin rate for spin-stabilized projectiles, a canard guided dual-spin stabilized pro-jectile concept is studied. Several aspects regarding the two-dimensional trajectory correc-tion theory and related key technologies of such a dual-spin projectile are investigated, in-cluding flight dynamics modeling, flight stability analysis, trajectory detection and recon-struction technologies, guidance and control methods, etc.The general form of seven degree-of-freedom (7DOF) equations of motion for the du-al-spin projectile is established in the fixed-plane reference frame by the Newton-Eulermethod, and the simplified form of7DOF equations of motion is developed when the du-al-spin projectile is mass balanced. Then the expressions of applied forces and moments areprovided and a numerical simulation study is carried out.The differential equation for the complex angle of attack is derived by the use of theprojectile linear theory and Murphy’s complex variable method, including the measurableeffects of Euler pitch angle. A revised flight stability criterion is established according tothe Hurwitz stability criterion and expressions of the stability boundaries for trim angles aredeveloped. The new stability criterion takes into account the effects of canards and extendsthe conventional projectile stability theory. It can account for the possible flight instabilityof projectiles subjected to side forces applied at the nose, and can be reduced to the sameform as the conventional spin-stabilized projectile case. Moreover, detailed trajectory sim-ulations of the155mm dual-spin projectile indicate that the new stability criterion givessatisfactory agreement with numerical results, which further demonstrates the effectivenessof the stability criterion.A scheme of GPS/MIMU integrated system is proposed for the dual-spin projectile tra-jectory detection. In this scheme, GPS and MIMU are integrated using a loosely coupledarchitecture, and the filter processes the position and velocity errors to feedback correctioninformation for MIMU. Due to the short-time and short-distance navigation for the du-al-spin projectile, mechanization and error equations for MIMU are founded in the launchcoordinate system, together with the filter model. In view of the model nonlinearity, theunscented Kalman filter (UKF) is selected as the data fusion tool. Trajectory reconstructionexample shows that the proposed GPS/MIMU integrated system can provide accurate flight parameters online for the dual-spin projectile, and it can achieve a satisfactory accuracy atthe presence of the interrupt of GPS signal.In order to reliably track the sinusoidal modulation guidance commands with variationsin frequency for the dual-spin projectile, a canard tracking servo controller is designed interms of the generalized asymptotic regulation, and subsequently the control commandpre-compensation method is adopted to blunt the effects of the coupling between longitu-dinal and lateral movements on trajectory correction. A set of linear matrix inequality con-ditions that guarantee generalized asymptotic regulation are derived and the synthesis of alinear time-invariant controller is provided. The order reduction by balanced truncation ofthe synthesized controller is considered based on the stability criterion. Simulation resultsshow that the designed controller with reduced order can track the sinusoidal commandswith variations in both frequency and amplitude with high accuracy and fast response speed.Meanwhile, it can attenuate the loading moment disturbance very well and can be imple-mented easily in practice. Although the adopted control command pre-compensation meth-od cannot realizes the completely dynamic decoupling of longitudinal and lateral move-ments, it is simple and feasible from engineering point of view, and can further improve thecorrection accuracy for the dual-spin projectile.Finally, the principle of guidance of the dual-spin projectile is deeply analyzed and theimplementation of trajectory tracking (TT) guidance law and modified proportion naviga-tion (MPN) guidance law is investigated. According to the source of the dominated normalforce produced by the dual-spin projectile, the ways to control the movement of center ofmass are divided into two categories, direct and indirect control, which can be distinguishedby the sign of the proposed maneuverability factor. In order to evaluate the guidance per-formance of TT and MPN guidance laws, they are both used to guide the155mm dual-spinprojectile to hit the target. Monte Carlo simulation results show that TT and MPN guidancelaws can significantly reduce the impact point dispersion of uncontrolled trajectory due toimperfect launch and interference of random winds, and the MPN guidance is superior indispersion reduction, but TT guidance can obtain higher accuracy. The presence of meas-urement errors may increase the circular error probability of the two guidance laws, butthey can still reduce the ballistic delivery errors very well.